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Padlocks – A Full Guide to the Different Types, Their Uses and Security Ratings

The different parts of a padlock

With countless different styles, sizes and applications of padlock available it may surprise you to know that the basic principles of their function and design are all pretty much the same.

Although the bodies of certain types of padlocks (some disc or combination padlocks, for example) are made from alternative materials, the majority of padlocks have a solid metal body. The solid padlock body is by far the strongest part of the padlock and, as a general rule, the larger the body the larger and more substantial the locking mechanism can be.

The U-shaped metal bar that exits and re-enters the padlock body is called the shackle or shank. Whilst the body of the padlock is relatively well protected this part of the lock is exposed and therefore most vulnerable to attack. As with increasing the size of the body, incorporating a more substantial shackle into a design a considerably more secure padlock can be produced. Whilst most padlocks use a spring-loaded shackle mechanism, certain others incorporate a manually released shackle.

Now for the business end of the padlock, the locking mechanism and key-way. Usually made up of between 3 and 7 tiny spring loaded pins, the unique key entering the padlock’s barrel causes these pins to be precisely aligned, in turn allowing the barrel to rotate, releasing the shackle.

As previously mentioned, most padlocks follow roughly the same principles of design. Having said that, certain other products do have slightly different properties. Continue reading this document explaining the different designs and merits of each.

Types of padlocks

There are countless designs of padlocks on the market and many of them can be found on this site. Each of these padlocks has unique and interesting features that set it aside from all others in terms of design, convenience and security.

The Closed Shackle Padlock

An increasingly common design of padlock on the market, the name ‘closed shackle’ padlock simply implies that the normally vulnerable shackle has been protected in some way. In doing so the manufacturer has made it considerably more difficult to defeat these padlocks with either bolt cutters or a saw. Crucially, many insurance companies demand the use of such closed-shackle padlocks as an absolute minimum security measure.

It is worth noting, however, that in protecting the shackle in such a way it can frequently reduce the flexibility and ‘usable clearance’ of the padlock. By ‘usable clearance’ we mean the area between the shackles that allows us to pass them through a hasp or hole, around a bar or, indeed, onto a cable. As a result it is vitally important that you check not only your own requirements but also the exact dimensions on our website prior to making your purchase.

The Straight Shackle Padlock

Another commonly used design is the ‘straight shackle’ padlock, otherwise referred to as shutter padlocks because of their common application for securing roller-shutter doors, something for which they are perfectly suited.

It is wrong to assume that this is their only purpose, however. Indeed, the straight shackle padlock is an incredibly versatile product having a wide variety of uses – from securing warehouse doors to shipping containers – due to their design and the levels of both security and convenience that this results in.

The Discus or Round Padlock

Frequently referred to in the industry as a ‘closed shackle padlock’, the term refers to the long, curved shackle that wraps securely around the entire body of the lock. This precise feature is exactly what makes the discus, circular or round shackle padlock pictured here so resistant to attacks from tools such as bolt cutters.

Otherwise known as ’round shackled’ or disc padlocks, these locks are circular and have a curved shackle that encompasses the entire body of the lock. This precise feature is exactly what makes the discus, circular or round shackle padlock pictured here so resistant to attacks from tools such as bolt cutters.

That said, whilst more conventional padlock designs incorporate a solid body, this type of lock has a circular shackle enclosed between two metal cases that combine to produce a disc, the keyway being placed directly in the middle of one disc. Due these locks’ non-spring-loaded nature, they are relatively safe from drilling or other excessive force and will most often remain firmly locked.

It is worth bearing in mind that these discus padlocks were originally intended to be used in conjunction with a staple and hasp, thereby covering the albeit small part of the shackle that would have been otherwise exposed. Clearly this makes it even more difficult to be cut, hammered, sawn or bolt cropped.

WARNING: In recent times many budget padlock manufacturers have released products that have sullied the reputation of those high-quality locks that have become known for their high levels of security. Indeed, a number of these cheaper, flimsier locks can be defeated simply by hammering on the join between the halves of the circular body. Unfortunately this has become a fact widely known amongst the criminal fraternity who use this technique regularly to smash the lock and expose the mechanism inside.

It is worth noting that this site only sells high quality locks such as the ‘ABUS Diskus’ range that are not susceptible to such attacks. This lock and those from other premium brands incorporate a disc of hardened steel within the case that stops the body of the padlock from being smashed. As a result the ‘ABUS’ range of disc padlocks sold on this site are the leading discus padlocks on sale today.

Long Shackle Padlocks

Simply a traditionally designed, solid bodied padlock with a longer, extended shackle, this feature adds an element of convenience by increasing the locking area and thereby the number of potential applications. This added convenience can lead to a corresponding reduction in the lock’s security rating. Quite simply, because of the exposure of the shackle the lock is more susceptible to attacks by bolts cutters and saws.

Combination or Coded Padlocks

We are frequently asked if combination padlocks are as secure as keyed padlocks. Quite simply the answer is no. Due to the very nature of a combination mechanism, such padlocks can never be as strong as a decent keyed equivalent. Also, whilst a relatively unlikely occurrence, a combination can always be cracked over time simply by trying out each possible combination of numbers one after another. As a rule a 3-dialled lock with 10 numbers per dial can be opened within 40 minutes with a 4-dialled lock taking somewhat longer in 4-5 hours.

As a result, insurance companies will rarely cover your property or possessions when they are protected by a combination padlock. That is not to say, however, that these locks are not a hugely useful tool in the right circumstances. One obvious advantage is seen when a number of users need access to a single place with another benefit arising from eliminating the need to carry a key around at all times.

A further convenient security factor is afforded by being able to reset and change the combination of the padlock at any time – whilst unlocked of course. That said, there have been occasions when a single malicious and yet authorised user has reset the code to suit their own ends. To combat this issue a number of manufactures have introduced a feature that prevents the combination from being reset without a key.

Weather Proof Padlocks

A completely weatherproof padlock – frequently known as the ‘marine’ padlock due to their suitability for salty and other extreme environments – is a lock that consists of 100% stainless steel and non-corrosive materials.

With many padlocks being constructed from more vulnerable materials, the obvious weak link across nearly all padlock types is the internal mechanism, a series of tiny springs and pins that, when rusted, will stop the lock from operating correctly and ultimately stop the lock from functioning at all.

That is not to say that many ‘non-marine’ padlocks are not ideally suited to outside use due to the fact that many high-quality locks have been developed using non-corroding materials. A prime example of this would be the range of ABUS padlocks sold here on this site, a series of padlocks constructed using only the best quality of marine grade materials.

The Choice Between Weatherproof and Security

Why would you choose a standard, more traditional padlock if a marine padlock is so very secure? Put simply, completely non-corroding materials such as those used in the manufacture of marine padlocks are softer than those used for conventional locks. As a result the shackles of these locks can be cut, sawn through or bolt cropped more easily. It is vital that you consider this factor very carefully before you choose which padlock to use.

Whilst the exposed shackle may discolour over time, the conventional type of padlock would generally be a better option for normal outdoor use. Whilst this discolouration may worry some customers it is nothing to worry about as the corrosion they see will not affect the functionality of their lock.

As with most things in life, however, there are exceptions to this rule. The ABUS Granit series padlocks found on this site are actually manufactured using fully marine-grade materials, are cataphorically coated and therefore able to cope with incredibly extreme environments for over 80 years.

All things considered, however, if you are planning on leaving your lock unattended for long periods of time, by the sea, on a boat or in areas with extreme environments we would always recommend you use a fully marine-grade padlock. To make it easy to find locks like these on our site, any padlock with the ‘raindrop’ icon is classed as fully weatherproof.

Some types of padlocks offer even greater levels of protection by including an external protective plastic jacket and a shielded keyway. You will find that this specific type of padlock is frequently marine grade or ‘weatherproof’ and present a suitable option for those wishing to guard their lock from moisture be it from precipitation or other elements.

Insurance Rated Padlocks

More and more often insurance companies are requiring policy holders to install specific types of padlocks, often ones with minimum security ratings. Whilst this will depend upon your individual insurance firm the majority of them will adhere to a similar set of basic requirements, most insisting that the insured used a ‘closed shackle’, keyed design rather than a more traditional or combination style.

Quite often, however, underwriters will insist on padlocks that are towards the higher end of the industry standard for European padlock testing – the CEN grade. Whilst Level 6 padlocks frequently cost in excess of £100, they are easily the most secure padlocks on sale in the UK today.

The grading process undertaken by CEN is intended to effectively simulate a determined attack upon the padlock. Environmental effects and manipulation by humans are not included in these tests:

GRADE 6 – Maximum Security

GRADE 5 – Extra High Security

GRADE 4 – High Security

GRADE 3 – Medium Security

GRADE 2 – Standard Security

GRADE 1 – Low Security

Frequently criticised, this grading system is arguably rather flawed due to the fact that a padlock need only fail one of the test criteria to be awarded its lowest grade. One example of how this can affect an otherwise excellent, high security padlock is where the said lock may pass all tests with flying colours but may fail at minus 40 degrees centigrade, a temperature that would never be reached in most areas of the world.

Despite its flaws it is still a much more useful system of classification than simply defining a lock as ‘closed shackle’ as required by many insurance underwriters. Nothing But Padlocks stock a number of open-shackle padlocks that are 2 levels higher in the European CEN scheme than some of our (traditionally more secure) closed-shackle locks.

If you find yourself with this problem and discover that a closed-shackle padlock just won’t work, why not consult your insurance company and they will provide you with the relevant BS EM or CEN grading.

Can A Padlocks Be Picked?

It is an inescapable fact that any padlock can be picked by a true expert. Some padlocks, however, are more easily picked than others. Reassuringly though, even the greatest locksmiths can spend hours picking the cream of the modern padlocks.

The workings of a padlock are not as simple as many would imagine. Inside is a series of spring-loaded pins of varying lengths which are aligned as the notches cut into the key move over them. It is technically possible to adjust these pins (using specialised lock picking tools) into such a position that the padlock will open.

Unfortunately, due to their smaller dimensions and the correspondingly smaller number of pins, smaller padlocks are usually easier to pick. As a general example, a 50mm lock could contact around 4-7 locking pins whilst a smaller, 30mm device would only use 3-4.

This is not to say that smaller padlocks will not be particular secure, not at all. Knowing the limitations of their locks all too well, the premium manufacturers of padlocks have come up with a number of devices that help prevent manipulation by outside elements – commonly known as criminals. Split pins with mushroom-shaped heads, guarded keyways and completely ‘pinless’ locking mechanisms are just a few of those anti-manipulation devices that now mean any high-quality padlocks, regardless of size, will be resistant to almost any thief or lock-picker.

However, when it comes to securing truly valuable items it is always worth going for the very best, something that will defeat even the most experienced lock smiths around. Both ABUS and Abloy, for example, have devised ingenious padlock lock cylinders for the padlocks that now use rotating discs instead of pins. Those very ABUS padlocks are available on this site and are referred to as the ‘Granit Plus’ range. With these discs rotating around 360 degrees, compromising such a padlock is near impossible. Furthermore, a malicious keyholder can’t simply get another key cut to further their own ends. These padlocks come with a unique code card that must be presented to an authorised locksmith before another key can be cut.

Keyed Alike and Master Key Padlocks

Whilst the majority of padlocks can only be opened by a single key it is frequently useful to have a number of padlocks that can be unlocked by a single master key.

At manufacture most padlocks are what the industry refer to as ‘Keyed Different’ meaning that the locking mechanism of each lock produced by that manufacturer is chosen at random. Usually this translates to 2 out of approximately 500 locks working with the same key. Clearly the number of duplicates will fall along with the number of locking pins used in the lock, i.e. if the padlock in question is a smaller device with fewer locking pins there will probably be more duplicates in existence. The same applies to many budget padlocks where quality control and accuracy are more in question.

Keyed Alike

There is also another type of padlock, only marginally more expensive than keyed-different locks, called ‘keyed alike’. Due to their minimal price difference they have become incredibly popular purchases for the customer who needs one key that can open the same ‘suite’ of padlocks. The term ‘suite’ refers to a series of identical padlocks.

“Does this compromise security?”… a commonly asked question and one that makes a lot of sense considering that more people will have access to the keys. Quite simply the answer is yes, more people will have access to the key but, for many of our customers, that price is worth paying for the added convenience.

If this does concern you it is possible to reduce this risk by choosing a lock from one of the premium manufacturers. Most of these firms will have a number of key-sets available thereby reducing the level of risk to the security conscious customer. As a padlock specialist we take steps to further mitigate the risk inherent in keyed-alike padlocks by stocking a number of these key-sets and rotating them on a regular basis.

Master Key

For a compromise between ‘keyed-different’ and ‘keyed-alike’ padlocks there is always a third way – ‘Master-keyed’ padlocks. In this case each lock has its own key but is part of a larger group which can all be opened by one common key, or master. As long as the master key is kept tightly locked away the whole set should be perfectly secure.

Clearly with this increase in security comes an increase in cost if only because of their added complexity. When a combination of both convenience and security is essential the master-key setup is ideal.